Typewriting machine



Sept. 4, 1945. w. F. HELMOND.

TYPEWRITING MACHINE Filed March 8, 1944 I flit "Vb INVENTOR Wmmm, 9". WM

TTORN'EY- Patented Sept. 4, 1945 TYPEWRITING MACHINE William F. Helmond,CIinton,QConn., as signor to Underwood Corporation, a corporation ofDelaware Application March 8, 1944, Serial No. 525,807

- i 2 Claims.

: 'This'; invention relates to type bars for typewriters and likemachines, in which the types when actuated start from differentpoints ofan arcuate array and move in converging pathsto strike at a commonprinting point.

In typewriters of this kind clashing or catching of the type headsduring the rapid succession of type bar strokes sometimes occurs. Thisis sometimes due to a particular construction of the composite typ bar,which makes necessary an abrupt shoulder at the back of the type headwhere same is joined to the type bar proper. During speedy operation ofthe typewriter, the type face of the next-succeeding type bar, moving.toward the printing point, occasionally clashes with this shoulder ofthe first-operated type bar as the latter is receding from the printingpoint, often causing serious damage to the type face.

The main object of the invention is to provide an improved constructionby which this clashing or catching of the type head is prevented, to theend that damage to the type face is avoided if the type bars shouldcollide.

More specifically, an object is to provide an improved composite typebar in which the type bar proper affords a transversely converging orlaterally tapered form trailing the type head block and resenting a faceon each side of the type bar that is substantially a continuation of,and flush with, the type head side.

Another object is to provide a type bar with a tapered portion trailingthe type head, of such construction that the tapered portion, althoughsubstantially broader than the thickness of the type bar stock, may beformed from the same sheet metal stock, and if desired, may be producedin the same stamping operation in which the type bar itself is produced.

Other objects will be apparent as the following description of apreferred embodiment of the invention proceeds.

In the drawing:

Figure 1 is a fragmentary transverse sectional view illustrating atypical arrangement of the type bars in a typewriter embodying theinvention,

Figure 2 is an enlarged detail view of the improved type bar,

Figure 3 i an enlarged sectional view taken on line 3-3 of Figure 2,

Figure 4 is a sectional view taken on line 44 of Figure 2, and,

Figure 5 is a top view illustrating the operation of the invention inpreventing catching of the type bars.

The invention is particularly advantageous in front-strike typewritingmachines in Whichthe type bars move to the platen in convergent'paths.One example is shown in Figure 1, in which type bars 6 are pivoted on'an arcuateaxis 1 and are guided by slots in a segment plate 8, to movein paths converging on the printing point. When actuated, the type barswings toward a platen 9, first striking an anvil IO' and then Whippinginto printing engagement with a work sheet on the platen. The fullcomplement of the type bars at rest have the type heads H disposed in anarcuate array and when actuated to print; move in respective paths allconvergent at a common printing point defined by a type guide I2. A lipl3 on each type bar-cooperates with the type guide l2 in the usualmanner to bring the type head exactly to the printing point.

In Underwood typewriters the type head ll and the arm 14 composing thecomplete type bar, are separate pieces, as shown more clearly in Figure4. The arm I4 is produced by stamping, from relatively thin sheet-metalstock, usually by a single stamping operation. The type head ll requiresa substantial thickness, several times that of the type arm M, to affordan adequate area for the type and a hammer effect in printing. Tosecurely mount the type head, same has a slot l5 of appreciable depthand of a width to receive the type arm, on which the type head is firmlysecured, preferably by soldering the adjacent surfaces within the slotl5.

It will be observed that this construction and assembly of the compositetype bar results in having an abrupt shoulder I6 along the trailing edgeof the type head. The members of the type head on each side of the slotl5 necessarily have a substantial thickness throughout to assureruggedness and, although some tapering toward the back edge ispermissible as shown, the eliminationof the shoulder l6 by tapering, sayto a feather edge, is impractical. In typewriters heretofore in use,having type bars constructed similar to the above, damage to type faces,such as deforming the serifs, has resulted from the nextactuated typehead striking the shoulder I6 of the preceding type head before thelatter could recede sufficiently from the platen.

It is well known to guard against damage to the type faces resultingfrom edge-to-edge collision of the type bars by providing a prongprojecting rearwardly from the type head. This feature, per se, isincluded in the embodiment shown, to complete the illustration of thetype bar structure. The type bar is extended at IT,

back of shoulder l6, to-form a projecting rounded thickest type headwill be suitable for all.

point or prong l8 reaching somewhat back of l the adjacent longitudinaledge of the arm, with the edges of the extensions diverging from saidpoint. Should one type head collide with the back edge of another,damage to a type face is avoided by the rearward prong l8 of. theleading type bar engaging the colliding bar at an area between the upperand lower-case type faces;

As afore indicated, the present improvements, now to be described, aredirected to avoiding damage to the type face resulting from collisioncording to the invention, the portion ll trailing the type head isenlarged or expanded laterally so that the outermost surfaces of the armat this portion are substantially flush with the side faces of the typehead. To provide this enlargement,

the extension ll is extruded at 20 and 2| in op-- posite lateraldirections to form a, rib or boss at each side of the type bar. Eachboss 20, 2| begins just back of the type head shoulder l6 where itsouter face is substantially flush with, and, :forms a continuation of,the type head side.

Each boss may project slightly beyond the type head, as shown, so as tobe adequate for type heads of abnormal thickness. If the type headsofall the characters vary materially, as is usual in some typewriters,bosses adequate for the In this way uniform type arms, insofar as otherjwise'practicable, may be used. From its end ad- .sideways, particularlyat the shoulder "16. -Accollisions, as shown in Figure 5, the bosses 20,2| avoid this damage. As the two type bars come together, the bossdeflects the type head of the rearmost type bar so that its type-facewill not strike or catch on the shoulder IE, but will continue past thetype bar, after only a light glancing impact at the sides. The taper ofthe bosses, as wellas otthe. type head, is so, gradual that only a,light impact results as the two type bars engage each other. 7

What is claimed is:

1. In a type bar assembly for front-strike typewriters, having arelatively wide type head with rearwardly extending side membersaffording a slot therebetween, and a relatively thin, sheetmetaltype-carrying arm secured in the slot of the type head and having aportion substantially trailing the type head; the'improvement of.providing at least one boss on each side of the trailing portion of thetype arm, each boss extending rearwardly from a point just back of thetype head side member, atwhich point the boss is substantially flushwith said member, and each boss being tapered rearwardly to grade intothe thin body of the arm at its trailing extremity.

2. In a type bar assembly for front-strike typewriters, having arelatively wide type head with rearwardly extending side membersafiording a slot therebetween, and a relatively thin,sheetmetal'typecarrying arm secured in the slot of the type" headandhaving a portion substantially trailing thetype head; the improvementof providing two oppositely directed extrusions in adjacent areas ofthe'trailing portion of the type arm; each extrusion forming a ridgestarting just rearward of type head side member and substantially flushwith said member, each ridge being inclined longitudinally'to blend intothe thin sheet forming the trailing extremity of the type nnc WILLIAMl5". HELMOND.

